1. Field of the Invention
The invention relates to the technical field of data recognition, and, more particularly, to a document with isotropic indexes and associated document reader system.
2. Description of Related Art
To increase convenience, interest and availability to read a document printed on an object such as paper or the like, a typical process embeds indexes in pictures printed on a document, uses an external reader to read an index corresponding to a part of pictures, and activates an output device to generate, such as a sound output, in accordance with the index read by the reader, thereby effectively helping reading by the sound. However, due to the embedded index in pictures on the document, it causes complicated document production and affects picture presentation. Further, how indexes are read accurately without picture affection is a problem to be solved.
U.S. Pat. No. 5,416,312 granted to Lamoure, et al. for an “Document bearing an image or a text and provided with an indexing frame, and associated document analysis system” superimposes a layer of indexes with plural dots on a source image. As shown in FIG. 1, an index 10 consists of five active rows and five blank rows. The active rows contain the encoding locations 30 and the empty encoding locations 31. Such an index 10 can represent different picture objects, which can be read by an optical reader system for post processing. For example, indexes representing different picture objects are associated with speeches so that a speech corresponding to a picture object is played as the optical reader system reads the picture object.
However, in U.S. Pat. No. 5,416,312, the index 10 arranges plural print dots in a matrix and orthogonal form. However, such an arrangement may cause incorrect reading on twisted pictures. Namely, when the document with the index 10 is slightly twisted, the optical reader system cannot read the index 10 accurately. In addition, an X-Y coordinate has to be applied to the optical reader system for accurately determining an orientation of the read index 10 and identifying the index orientation along with multiple codes. Further, the prior art superimposes the index 10 on the printed pictures, which limits the printing procedures and wastes time.